Conventionally, as an electrochemical sensor, for example, a compact sodium ion meter C-122 and a compact nitric acid ion meter B-343 both of which are manufactured by HORIBA, Ltd. and the like have been commercially available. When a user intends to perform measurement using such an electrochemical sensor, the electrochemical sensor is calibrated using standard liquids for calibration in advance for ensuring accuracy in measurement.
For example, when the compact sodium ion meter C-122 is calibrated in accordance with one-liquid calibration, calibration is performed in accordance with the following steps. (1) The sensor (meaning a sensor head, this definition used hereinafter) is cleanly washed using a cleaning liquid, and the cleaning liquid is wiped away using dry tissue paper or the like. This cleaning operation is repeated a few times. (2) A sampling sheet is placed on the sensor, and an STD standard solution (first standard solution) is dropped on the sampling sheet (may be directly dropped on the sensor). (3) After the sensor becomes stable, a display of the sensor is adjusted to 20×100 by an STD volume. (4) The sensor is cleaned using a cleaning liquid and, thereafter, the cleaning liquid is wiped out by dry tissue paper or the like (calibration finished).
When the compact sodium ion meter C-122 is calibrated in accordance with two-liquid calibration, calibration requires an operation where an SLOPE standard liquid (second standard liquid) is additionally used, and a display of the sensor is adjusted to 15×10 by a SLOPE volume.
The same calibration steps are performed also with respect to calibration of the compact nitric acid ion meter B-343.
Such calibration is extremely cumbersome for users in general and there also is a possibility that an error will occur during the operation.
In view of the above, conventionally, as described in Japanese Patent Laid-open Publication No. 2009-150902, there has been proposed a device where a spike is mounted on a sample holding chamber in the inside of a cartridge to be inserted into a reading device, a package (a foiled pack filled with a standard liquid for calibration) is broken by the spike when a user inserts the cartridge into the reading device, and a liquid is introduced into a conduit from the sample holding chamber. With the use of such a device, the user can perform calibration automatically by merely inserting the cartridge into the reading device even when the user does not perform the operations for calibration intentionally.